Effect Of Preparation Protocol Research Articles

Enhancement of perchlorate removal from groundwater by cationic granular activated carbon: Effect of preparation protocol and surface properties

In order to obtain a high adsorption capacity for perchlorate, the epoxide-forming quaternary ammonium (EQA) compounds were chemically bonded onto granular activated carbon (GAC) surface by cationic reaction. The optimum preparation condition of the cationic GAC was achieved while applying softwood-based Gran C as the parent GAC, dosing EQA first at a pH of 12, preparation time of 48 h, preparation temperature of 50 °C, and mole ratio of EQA/oxygen groups of 2.5. The most favorable cationic GAC that had the QUAB360 pre-anchored exhibited the highest perchlorate adsorption capacity of 24.7 mg/g, and presented the longest bed volumes (3000 BV) to 2 ppb breakthrough during rapid small scale column tests (RSSCTs), which was 150 times higher than that for the pristine Gran C. This was attributed to its higher nitrogen amount (1.53 At%) and higher positive surface charge (0.036 mmol/g) at pH 7.5. Also, there was no leaching of the quaternary ammonium detected in the effluent of the RSSCTs, indicating there was no secondary pollution occurring during the perchlorate removal process. Overall, this study provides an effective and environmental-friendly technology for improving GAC perchlorate adsorption capacity for groundwater treatment.

Effect of preparation protocol on physicochemical features and biointeractions of pegylated liposomes

Poly(ethylene glycol) (PEG) stabilized liposomes are widely used in drug delivery research because these surface grafted polymers stabilize liposomes in blood stream. However, hydrophilic polymers also affect lipid membrane organization and it is fundamental to investigate their effect on the physicochemical properties of lipid bilayers as well as on their interaction with biological membrane. PEG monolaurate was included in liposomes formulated with dimyristoyl-sn-glycero-3-phosphocholine and one of two cationic gemini surfactants that differ each other for the configuration of a stereogenic center on the polar headgroup. These formulations previously showed good efficiency as drug and DNA delivery systems. The effect of the presence of different amounts of a PEG-lipid and of the liposome preparation protocol was investigated by turbidimetry, dynamic laser light scattering, differential scanning calorimetry and electrophoretic mobility. Flow cytometry and laser scanning confocal microscopy on murine (C6) and on human glioblastoma (LN229) cell lines were also carried out to evaluate the influence of pegylation and of the protocol of preparation on the interaction of liposomes with the biological milieu.

Effect of preparation protocol on the surface acidity of molybdenum catalysts supported on titania and zirconia

Molybdenum catalysts supported on titania and zirconia have been prepared via the impregnation on the corresponding hydroxides and oxides. The solids have been characterized by surface area measurements, XR-Fluorescence analysis, XRD and Raman Spectroscopy. The isopropanol decomposition reaction has been used to probe their acidic properties. These analyses revealed that introduction of molybdenum on the surfaces of the hydroxides and the oxides results in an increase of the specific surface area. Impregnation on the hydroxide leads to a comparatively better molybdenum dispersion and to a greater surface acidity. This indicates that the acid sites on hydroxide derived solids are stronger and more numerous than on their oxide derived counterpart.

Statistics and Properties of Low-Frequency Vibrational Modes in Structural Glasses.

Low-frequency vibrational modes play a central role in determining various basic properties of glasses, yet their statistical and mechanical properties are not fully understood. Using extensive numerical simulations of several model glasses in three dimensions, we show that in systems of linear size L sufficiently smaller than a crossover size L_{D}, the low-frequency tail of the density of states follows D(ω)∼ω^{4} up to the vicinity of the lowest Goldstone mode frequency. We find that the sample-to-sample statistics of the minimal vibrational frequency in systems of size L<L_{D} is Weibullian, with scaling exponents in excellent agreement with the ω^{4} law. We further show that the lowest-frequency modes are spatially quasilocalized and that their localization and associated quartic anharmonicity are largely frequency independent. The effect of preparation protocols on the low-frequency modes is elucidated, and a number of glassy length scales are briefly discussed.

Effect of preparation protocol on anchoring quaternary ammonium/epoxide-forming compound into granular activated carbon for perchlorate adsorption: Enhancement by Response Surface Methodology

A novel method has been developed for anchoring quaternary ammonium/epoxide-forming compounds (QAEs) within bituminous based granular activated carbons (GACs). This modified GAC was then used to remove perchlorate from groundwater. The effect of the preparation temperature (T), solution pH (pH) and the dry mass ratio of QAE-to-GAC (R) over the perchlorate adsorption capacity (Qe) were studied by the Response Surface Methodology. The combined effects of these variables were fitted to a quadratic model to determine the more favorable preparation protocol for perchlorate removal. Statistical analysis revealed that: (1) the interaction of T and pH incurred the most effect on Qe; and (2) two of the more favorable preparation protocols became apparent: one was at 75°C, pH 11 and R of 1.73g QAE/g GAC (U17), the other was at 35°C, pH 14 and R of 4.00g QAE/g GAC (U2). Rapid small scale column tests were further employed to evaluate the performance of the QAE-anchored GACs for perchlorate removal. U17 and U2 exhibited 18–20 times longer bed life (BV) to 6ppb breakthrough than did the Pristine GAC (900BV), when processing groundwater that had been spiked with 30–35ppb perchlorate. This indicated the statistical method enhanced GAC’s perchlorate removal efficiency.

In vitro optimization of liposomal nanocarriers prepared from breast tumor cell specific phage fusion protein

Fusion proteins created by phage display peptides with tumor cell specificity and the pVIII major coat protein of filamentous phages have been explored recently as a simple and cost-effective means for preparing tumor-targeted liposomes that improve the cytotoxicity of anticancer drugs in vitro. The next step in the development of this approach is the optimization of the liposome composition for the maximum targeting activity and subsequent testing in vivo. This study aimed to investigate the impact of preparation protocols, lipid composition and phage protein content on the targeting efficiency of phage protein-modified liposomes. Analysis of size, zeta potential and morphology was used to investigate the effect of preparation protocols on the stability and homogeneity of the phage liposomes. A previously developed coculture targeting assay and a factorial design approach were used to determine the role of lipid composition of the liposomal membrane on the target cell specificity of the phage liposomes. Western blot combined with proteinase K treatment detected the orientation of targeted phage protein in liposomal membrane. Phage protein, DPPG and PEG2k-PE showed positive effects on target specificity of phage liposomes. The results served to identify optimal formulation that offer an improved liposomal affinity for target tumor cells over the non-optimized formulation.

Modification of NAY by LA3+ for the dehydration of lactic acid: The effect of preparation protocol on catalyst microstructure and catalytic performance

AbstractLa‐modified NaY zeolites have been prepared through impregnation and in situ synthesis methods. The surface structure of the obtained zeolites was then characterised by XRD, UV–Vis DRS, FT‐Far‐IR, Raman spectra, H2‐TPR, N2 adsorption, and NH3‐TPD. The results of the catalytic dehydration reaction of lactic acid showed that the La/NaY catalyst prepared by impregnation method exhibited higher selectivity to acrylic acid than the La–NaY prepared by the in situ synthesis. The characterisation results indicated that the enhanced catalytic performance could be attributed to the difference of La3+ ion location caused by the different preparation protocols, which would influence the electric field distribution of zeolites cages, the reactant adsorption, chemical activation, and the reaction path.Les zéolithes NaY modifiées avec du lanthane (La) ont été préparées grâce à des méthodes d'imprégnation et de synthèse in situ. La structure de la surface des zéolithes ainsi obtenues a été ensuite caractérisée par DRX, spectrophotomètre UV–VIS DR, FT‐Far‐IR, spectroscopie Raman, réduction thermo‐programmée de H2, adsorption de N2 et désorption thermo‐programmée de NH3. Les résultats de la réaction de déshydratation catalytique de l'acide lactique montrent que le catalyseur La/NAY préparé grâce à la méthode d'imprégnation a fait preuve d'une plus grande sélectivité à l'acide acrylique que le catalyseur La/NAY préparé grâce à la synthèse in situ. Les résultats de caractérisation indiquent que le meilleur rendement catalytique peut être dû aux différences d'emplacement de l'ion La3+ causées par les différents protocoles de préparation, qui peuvent influer sur la distribution du champ électrique des cages de zéolithes, l'adsorption du réactif, l'activation chimique et le chemin réactionnel. Can. J. Chem. Eng. © 2010 Canadian Society for Chemical Engineering